<template>
    <div class="goods-sku">
      <dl v-for="item in goods.specs" :key="item.id">
        <dt>{{ item.name }}</dt>
        <dd>
          <template v-for="val in item.values" :key="val.name">
            <img :class="{ selected: val.selected, disabled: val.disabled }" @click="clickSpecs(item, val)"
              v-if="val.picture" :src="val.picture" />
            <span :class="{ selected: val.selected, disabled: val.disabled }" @click="clickSpecs(item, val)" v-else>{{
                val.name
            }}</span>
          </template>
        </dd>
      </dl>
    </div>
  </template>
  <script>
  import { watchEffect } from 'vue'
  import getPowerSet from './power-set'
  const spliter = '★'
  // 根据skus数据得到路径字典对象
  const getPathMap = (skus) => {
    const pathMap = {}
    if (skus && skus.length > 0) {
      skus.forEach(sku => {
        // 1. 过滤出有库存有效的sku
        if (sku.inventory) {
          // 2. 得到sku属性值数组
          const specs = sku.specs.map(spec => spec.valueName)
          // 3. 得到sku属性值数组的子集
          const powerSet = getPowerSet(specs)
          // 4. 设置给路径字典对象
          powerSet.forEach(set => {
            const key = set.join(spliter)
            // 如果没有就先初始化一个空数组
            if (!pathMap[key]) {
              pathMap[key] = []
            }
            pathMap[key].push(sku.id)
          })
        }
      })
    }
    return pathMap
  }
   
  // 初始化禁用状态
  function initDisabledStatus (specs, pathMap) {
    if (specs && specs.length > 0) {
      specs.forEach(spec => {
        spec.values.forEach(val => {
          // 设置禁用状态
          val.disabled = !pathMap[val.name]
        })
      })
    }
  }
   
  // 得到当前选中规格集合
  const getSelectedArr = (specs) => {
    const selectedArr = []
    specs.forEach((spec, index) => {
      const selectedVal = spec.values.find(val => val.selected)
      if (selectedVal) {
        selectedArr[index] = selectedVal.name
      } else {
        selectedArr[index] = undefined
      }
    })
    return selectedArr
  }
   
  // 更新按钮的禁用状态
  const updateDisabledStatus = (specs, pathMap) => {
    // 遍历每一种规格
    specs.forEach((item, i) => {
      // 拿到当前选择的项目
      const selectedArr = getSelectedArr(specs)
      // 遍历每一个按钮
      item.values.forEach(val => {
        if (!val.selected) {
          selectedArr[i] = val.name
          // 去掉undefined之后组合成key
          const key = selectedArr.filter(value => value).join(spliter)
          val.disabled = !pathMap[key]
        }
      })
    })
  }
   
   
  export default {
    name: 'XtxGoodSku',
    props: {
      // specs:所有的规格信息  skus:所有的sku组合
      goods: {
        type: Object,
        default: () => ({ specs: [], skus: [] })
      }
    },
    emits: ['change'],
    setup (props, { emit }) {
      let pathMap = {}
      watchEffect(() => {
        // 得到所有字典集合
        pathMap = getPathMap(props.goods.skus)
        // 组件初始化的时候更新禁用状态
        initDisabledStatus(props.goods.specs, pathMap)
      })
   
      const clickSpecs = (item, val) => {
        if (val.disabled) return false
        // 选中与取消选中逻辑
        if (val.selected) {
          val.selected = false
        } else {
          item.values.forEach(bv => { bv.selected = false })
          val.selected = true
        }
        // 点击之后再次更新选中状态
        updateDisabledStatus(props.goods.specs, pathMap)
        // 把选择的sku信息传出去给父组件
        // 触发change事件将sku数据传递出去
        const selectedArr = getSelectedArr(props.goods.specs).filter(value => value)
        // 如果选中得规格数量和传入得规格总数相等则传出完整信息(都选择了)
        // 否则传出空对象
        if (selectedArr.length === props.goods.specs.length) {
          // 从路径字典中得到skuId
          const skuId = pathMap[selectedArr.join(spliter)][0]
          const sku = props.goods.skus.find(sku => sku.id === skuId)
          // 传递数据给父组件
          emit('change', {
            skuId: sku.id,
            price: sku.price,
            oldPrice: sku.oldPrice,
            inventory: sku.inventory,
            specsText: sku.specs.reduce((p, n) => `${p} ${n.name}：${n.valueName}`, '').trim()
          })
        } else {
          emit('change', {})
        }
      }
      return { clickSpecs }
    }
  }
  </script>
   
  <style scoped lang="scss">
  @mixin sku-state-mixin {
    border: 1px solid #e4e4e4;
    margin-right: 10px;
    cursor: pointer;
   
    &.selected {
      border-color: $xtxColor;
    }
   
    &.disabled {
      opacity: 0.6;
      border-style: dashed;
      cursor: not-allowed;
    }
  }
   
  .goods-sku {
    padding-left: 10px;
    padding-top: 20px;
   
    dl {
      display: flex;
      padding-bottom: 20px;
      align-items: center;
   
      dt {
        width: 50px;
        color: #999;
      }
   
      dd {
        flex: 1;
        color: #666;
   
        >img {
          width: 50px;
          height: 50px;
          margin-bottom: 4px;
          @include sku-state-mixin;
        }
   
        >span {
          display: inline-block;
          height: 30px;
          line-height: 28px;
          padding: 0 20px;
          margin-bottom: 4px;
          @include sku-state-mixin;
        }
      }
    }
  }
  </style>